Video-display-processor

ABSTRACT

A video-display processor produces an on-line display of the distribution density of radiation stimuli emitted by a radiation field utilizing a probe for detecting the stimuli and a counter for accumulating the number of stimuli detected; and motorized means to cause the probe to traverse the field and sequentially scan a preselected number of elemental areas, each having a preselected size, for causing the probe counter to accumulate the number of stimuli that occurred during the scan of each elemental area. The number of stimuli accumulated during the scan of each elemental area, upon the completion of the scan thereof is transferred into a memory whose contents modulate the picture elements of a raster generated by a CRT of a TV display thus displaying the density of each elemental area immediately after scanning thereof is complete.

United States Patent [191 Zukerman et al.

[451 Feb. 26, 1974 VIDEO-DISPLAY-PROCESSOR [75] Inventors: YoramZukerman; Moshe Ben-Porath; Benjamin Sabbah, all of Haifa, Israel [73]Assignee: Elscint Ltd., Haifa, Israel [22] Filed: June 26, 1972 [21]Appl. No.: 266,128

[52] US. Cl 178/68, 178/66 A, l78/7.6, l78/DIG. l, 178/DIG. 36, 235/92PC [51] Int. Cl H04n 3/04, H04n 5/76 [58] Field of Searchl78/6.8, 6.6 A,DIG. l, DIG. 36, 178/76; 235/92 PC [56] References Cited UNITED STATESPATENTS 3,643,015 2/1972 Davidovits l78/DIG. 37 3,629,495 12/197] Cahilll78/6.6 A 3,6I2,886 10/197! Hannig l78/7.6 3,579,249 5/l97l Deweyl78/6.8

OTHER PUBLICATIONS line Spacing "2" scale encode n X Shlft command Xcounter X counter up/oown ever Image Store N58," Siemens, Akg. Erlangen,Germany, June 1971.

Primary Examiner-Howard W. Britton Attorney, Agent, or Firm-Browdly &Neimark [5 7] ABSTRACT A video-display processor produces an on-linedisplay of the distribution density of radiation stimuli emitted by aradiation field utilizing a probe for detecting the stimuli and acounter for accumulating the number of stimuli detected; and motorizedmeans to cause the probe to traverse the field and sequentially scan apreselected number of elemental areas, each having a preselected size,for causing the probe counter to accumulate the number of stimuli thatoccurred during the scan of each elemental area. The number of stimuliaccumulated during the scan of each elemental area, upon the completionof the scan thereof is transferred into a memory whose contents modulatethe picture elements of a raster generated by a CRT of a TV display thusdisplaying the density of each elemental area immediately after scanningthereof is complete.

17 Claims, 8 Drawing, Figures ine spocmg Y SIIIH command outside memorylimits (mumur :nm mom memory are set distance pulse wrlte In memcrryorylsturt) PATENTEDFEBZB l974 3794.762

SHEET 2 [1F 4 I Left pulses RighT pulses set (down) (up) Fspeed K) II 5|8 |6 X II x H II x .i L -i Encoder motor control l Lefr llmiT Y Toplimit 12 l -l9 i? switch switch I "Y" Y "drive Encoder motor 25 20 X R1,down up I pulses pulses swnch "Y"moror Bottom limlf X direction 60mmSWlTCh Y direction Fig, 2 t line spacing (from "X" encoder) (from "Y"encoder) 'down up down up pulses pulses pulses pulses Reset X up/down 27Y up/down CTR. cTR.

V 0R8S6T 30 r 3| l f ll Yi xi x 2 H Y2 H Bo'rrom comporuTor compuraTorLOGIC Top limit swlfch SWH'Ch Xl X2 buffer buffer To "Y"mo1or control(switch dlreciioln 33 shift x2* 3 e Slliff XI 0 l Field 11 Left limilRT. limlr l swlrch swlTch To "X" moror conlrol (switch direction) Field.1

line o+l 'Field I line 0 PATENTEDFB26 m4 saw 3 or 4 line spacing "3"some X counTer Ycounter scale 2.5L. "'3'" encode n focfor up/downup/down factor m encoder x shiff Dump 44 Y shlfT command L command 1 Yourside X counTer Y counter outside memory dump dump memory limitslimits LOQIC 57 58 Logic riQhT Compurufor COmporoTor p down I g Y X. X2X Shh? CTR i Y 8h"? CTR'* reset 53 54 reset |o4 X T over t 105 coun er Ycoun er (memory) How (memory) -i I03 I02 shlfr mum memory Q re-ser Sisirunce l 59 pu se R 0 6O I wrlTe in memory Input Derecror counter 0Buffer dam -flpurse? mesa? distance pulse code"l 98 -J--[ I 2 I dlr. o1smnl|27|l2aH-- 106 A 64 f clear memorflsfurt) y 2 dir. of shiftl27ll28H- *wrife o Gl A l ls ol l R 3.024 MHZ 64 97 IO? 62 I I2 I gir.of snm||27||2a IO shift I I A main mem.

G 5 Decode G2 shift line refresh +-U |2| dir. of arm: ||27]|2e l "-Gl'3.024 MHZ 74 j 4 Q /|O9 65 73 75 G2 R to TV Logic g 4 1v 4 Adj.

1 VIDEO-DISPLAY-PROCESSOR This invention relates to avideo-display-processor for producing an on-line display of thedistribution density of radiation stimuli emitted by a radiation field.

The distribution density of radiation stimuli emitted by an organ of ananimal injected with a radio-active pharmaceutical is, in reality, a mapof the organ showing the quantity of pharmaceutical present in eachelemental portion of the organ. Maps of this type contain significantmedical information enabling those skilled in the field of nuclearmedicine to study, test and treat various organs of the body.

In order to obtain maps of this nature, it is conventional to immobilizethe patient beneath a probe which is caused to scan a region thatincludes the radiation field constituted by the organ to be mapped. Theprobe is capable of detecting radiation stimuli emitted by the organ,and includes a counter for accumulating the number of stimuli detectedduring the scan of each elemental area of the field.

The probe moves linearly at a constant speed in, for example, theX-direction from one limit to another, then is indexed in the Ydirection, and proceeds in the X-direction at the same speed to theoriginal limit where it is again indexed in the Y direction. Thereafter,the cycle is repeated until the probe has scanned the entire regionbetween limits in the X and Y directions. The linear speed of the probeand the spacing between line scans are dependent upon the resolution ofthe collimator associated with the probe and various medical parameterssuch as the type of organ, the radioactive isotope, etc. As aconsequence of all of these factors, a pulse is generated each time theprobe traverses a pre-set distance in the X-direction; and this pulse isused to effect the transfer of the contents of the counter associatedwith the probe into a buffer followed by a resetting of the counter. Atthe same time, a logic system establishes the address of the probe whenthe pre-set distance pulse occurs permitting the contents of the bufferto be transferred into a proper location in a memory of a computer.

After the scan is completed, a suitable program in the computer mayprocess the data contained in the memory using various techniques toenhance an understanding of a display thereof, and the processed data isthen made available for a black-and-white or color display on a CRTscreen. If the operator has selected the proper scan limits relative tothe organ to be mapped, and if the parameters of line spacing and linearspeed have been properly selected, the display will yield, to trainedpersonnel, the medical information being sought. If, on the other hand,the scan parameters were not properly selected, only a portion of theorgan may be mapped due to having selected improper scan limits, or themedically interesting area of the organ may be concealed byreason ofhaving selected the wrong scan speed. In either case, another scanprogram will have to be carried out. This is very wasteful bothmedically and economically.

In an effort to provide a technician during the scan operation with arough check on the quality of the selection of the scan parameters, itis conventional to utilize what is termed a dot-printer that provides arealtime display of the raw data obtained by the probe. A dot-printer isessentially an X-Y plotter that is slaved to the probe and is providedwith an output in the form of a hammer that prints a dot on a papersheet on contact. The number of times the hammer contacts the paper isproportional to the count (i.e., the number of radiation stimulidetected by the probe upon completion of the scan of an elemental areaof the radiation field). This expedient will usually indicate whetherthe limits of the scan have been properly chosen well before the scan ofthe radiation field is completed. If nec essary, the scan can beinterrupted, the relative position of the patient and the field scannedby the probe can be adjusted, and then a new scan can be commenced.

The dot printer also provides only a rather crude check on whether theprobe speed is proper under the circumstances because the output of thedot-printer is like a half-tone reproduction in which the resolutionwill depend upon the wisdom of the selection of the proportionalityconstant between the raw data derived from the probe and the hammer ofthe printer. F urthermore, since the dot-printer operates on the data asit is inserted into the memory and before it is processed to enhance itsunderstanding (e.g. before a constant is subtracted from the contents ofeach memory register to eliminate background noise), the dot pattern isonly an approximation that often conceals an incorrect probe speed thatbecomes apparent only after the scan is complete and the data processingcarried out.

While nevertheless improving the efficiency of obtaining a scan thatwill yield the sought after medical information, it is obvious that manymedical situations will arise in which there is simply no time toachieve more than one scan. In these cases, the raw data obtained may beinsufficient to provide the basis for reaching the necessary medicalconclusions. It is therefore an object of the present invention toprovide a new and improved apparatus which will not only process thedata as it is acquired to produce an on-line display in a form mostadvantageous for medical analysis, but also will permit the processingto be changed during acquisition of the data, and will permit the scanlimits to be adjusted before the scan is completed without losing any ofthe previously acquired data, thus eliminating the need to restart thescan.

According to the present invention, there is provided avideo-display-processor for producing an on-line display of distributiondensity of radiation stimuli emitted by a radiation field, comprising: aprobe for detecting the stimuli and a counter for accumulating thenumber of stimuli detected; motorized means to cause the probe totraverse the field and sequentially scan a preselected number ofelemental areas, each having a preselected size, for causing the probecounter to accumulate the number of stimuli that occurred during thescan of each elemental area; a memory; means for transferring into thememory the number of stimuli accumulated during the scan of eachelemental area upon the completion of the scan thereof; a TV displayhaving a CRT with a viewing screen and means to periodically generate araster of modulatable picture elements on the screen prior to completionof the scanning of all of the elemental areas of the field; and meansfor modulating the picture elements in accordance with the contents ofthe memory.

The beam of the CRT begins to generate a new raster at a rate which ismany orders of magnitudes greater than the rate at which scan data isacquired. Consequently, the number of stimuli occurring during the scanof a given elemental area of the radiation field can be stored in thememory, read-out, processed for enhancing the display, and used tomodulate the picture element corresponding to the given elemental areapractically simultaneous with its acquisition. The display thus buildsup, point-by-point as the scan progresses, permitting an early decisionto be made on whether to complete the scan or start a new one.

The memory is preferably constructed in the form of a plurality of shiftregisters whose contents are circulated through a complete cycle insynchronism with the generation of the TV raster, thus permittingcontrol to be exerted over the shifting of the memory prior to theinitiation of the generation of the raster. By shifting the memory priorto initiation of the generation of the next raster by an amount relatedto the shift of the limits of the probe, the data acquired prior to theshifting of the limits is retained and displayed in proper spatialrelationship to the data acquired subsequent to such shiftmg.

An embodiment of the invention is illustrated by way of example in theaccompanying drawings, wherein:

FIG. 1 is a block diagram of the video-displayprocessor according to thepresent invention;

FIG. 2 is a schematic block diagram of the logic for controlling themovement of the probe;

FIG. 3 is a schematic block diagram showing the logic by which limitsare established for the probe in both the X and Y directions;

FIG. 4 is a schematic block diagram showing the logic by which theoutput of the detector can be inserted into the proper location in thememory and the logic by which the contents of the memory may be read outfor the purposes of modulating the picture elements of the TV displaytube;

FIG. 5 is a combined chart and schematic representation showing thefield scanned by the probe as it relates to the memory and to thepictures presented on the television tube;

FIG. 6 is a block diagram showing apparatus for generating certaincontrol signals necessary for the operation of the logic shown in FIG.4;

FIG. 7 is a series of time diagrams showing the relationship of thevarious control signals to the TV sync signals; and

FIG. 8 is a schematic representation of a typical picture element on theTV tube.

Referring now to FIG. 1, reference numeral 10 designates avideo-display-processor according to the present invention comprising aprobe 11, motor means 12, a memory 13, a TV display tube 14, and meansfor controlling the operation of the various components.

Probe 11 preferably comprises a standard detector such as a 5 inchdiameter, 2 inch thick Nal (TI) crystal provided with a thin window thatefficiently transmits low energy photon radiation such as derived from LThe crystal is integrally assembled into unit with a 5 inch photomultiplier 9; and a suitable collimator 8 is provided in accordance withthe energy level of the source and the fineness of the focus decidedupon for medical reasons. The probe is positioned above an immobilizedpatient 7 previously injected with a radioactive pharmaceutical and inthe vicinity to receive radiation stimuli 6 emanating from the patientsorgan within which the pharmaceutical has been absorbed.

Motor means 12, shown best in FIG. 2, comprises a carriage (not shown)displaceable in the direction of the Y-axis and carrying a precisionshaft 15 whose rotation drives probe 11 in the direction of the X-axisthrough a linear distance proportional to the angular displacement ofthe shaft. Shaft 15 is driven by a motor 16 whose operation iscontrolled by control circuit 17. An encoder 18 associated with theshaft converts the angular rotation thereof to pulses that providedigital information on the X location of the probe and its direction ofmovement along the X-axis. The carriage is driven in the direction ofthe Y-axis by precision shaft 19 whose rotation by motor 20 iscontrolled by control circuit 21. Another encoder 22 associated withshaft 19 provides digital information on the Y location of the carriageand hence the Y location of the probe as well as its direction ofmovement along the Y axis.

In operation, motor means 12 drives the probe 11 in the X direction at aspeed dependent upon the maximum count rate in the area to be scanned,and such medical factors as the type of collimator and the scan timewithin which the scan must be completed. Encoders 18 and 20 each produceone pulse per unit distance traversed by the probe in the X and in the Ydirection, respectively. For example, each encoder may produce one pulseper 0.1 millimeter displacement of the probe, and the resultant pulsesappear at the up or the down terminals of the encoder depending upon thedirection of movement of the probe. The distance traversed by the probefrom one line in the X direction to the next line is termed the linespacing, and this parameter is also dependent on medical factors such asthe type of collimator, etc.

Two sets of constraints are imposed on the movement of the probe as itscans a radiation field. One set is established by the physicallimitations of the shaft 15 and 19, and such limitations are sensed bylimit switches 25 of which a pair are associated with the shaft 15 todefine the left hand right limits of the probe, and a pair areassociated with the shaft 19 to define the up and down limits of theprobe. The other set of constraints is established by the operator sothat a field less than the entire field defined by the limit switches 25can be scanned. For convenience, these limits are termed X1 and X2 inthe X direction, and Y1 and Y2 in the Y direction.

By reason of the logic of FIG. 3 the probe is caused to traverse thepath defined by lines 26 in FIG. 2. The control of the probe in the Xdirection is shown in detail in FIG. 3, it being understood that controlof the probe in the Y direction is similar. Pulses produced by encoder18 as the motor 16 drives the detector 11 in the X direction areaccumulated in up/down counter 27. When the contents of counter 27 isidentical to the contents of either of registers 28 or 29, theappropriate comparator 30 or 31 produces an output pulse which, if gate32 is enabled, causes the motor control 17 to switch the direction ofrotation of the motor 16. An operator selects the XL limit, for example,by providing a high level at line 33, thus enabling the transfer gateassociated with register 28, when the probe 11 is located at theappropriate displacement X1. In this manner, the contents of counter 27is transferred into the register 28 to establish the X1 limit.Similarly, the operator may select the X2 limit by providing a highlevel at line 34 which will transfer to the register 29 the contents ofcounter 27 when the probe 11 is at the desired X2 location. Havingselected the limits X1 and'X2 and set control flip/flops 35 to enablegates 32, the pulses derived from comparators 30 and 31 may pass throughthe gates 32 and effect the reversal of the X drive motor 16. In theabsence of selecting the limits X1 and X2, the closing of either theleft limit switch 25 or the closing of the right limit switch 25, willalso cause the motor control 17 to reverse the direction of rotation ofmotor 16.

Sometimes partially through a scan, an operator discovers that amedically interesting area is beyond the limits which have been imposedon the scan, and in such case provision is made for changing the limitsof the scan. For example, the limit X1 may be changed during the scantowards this limit when an operator de presses an X1 shift switch (notshown) and resets the control flip-flop 35 associated with the X1comparator 30 disabling the gate 32 associated therewith. The motor 16will thus be able to drive probe 11 beyond the original limit X1 becausethe pulse produced by the comparator 30, when the original limit X1 isreached, will be blocked by the disabled gate 32. The motor willcontinue to drive the probe, either until the left limit switch isreached or until the operator releases the shift switch applying a highlevel once more at line 33, setting flip/flop 35 and effecting thetransfer of the current contents of counter 27 into register 28. Theoutput pulse from comparator 30 will then pass through the newly enabledgate 32 thus changing the direction of the motor. The X2 limit may bechanged in a similar manner.

Before describing the manner in which data is acquired from theradiation field and displayed on the TV screen, reference is again madeto FIG. 1 in order to illustrate some of the design considerationsinvolved in the present invention. First of all, the present inventionis designed to utilize a television tube meeting the cur rent standardsof the F.C.C. in the United States. Such standards include a 525lineraster with each frame of the raster comprising two interlaced fields of262.5 lines each, each field being initiated by a vertical sync pulsewhose frequency is about 60 Hz. The line scan of the TV tube iscontrolled by horizontal sync pulses whose frequency is l5.75 KHz.

The tube 14 is oriented so that the raster lines are verticallypositioned rather than horizontally positioned as is usually the case,and the display is composed of 12,288 picture elements located betweenlines 34 and 226 (D2 lines in all) and covering about twothirds of thelength of each line. As shown in FIG. 8, two lines (a and a l) of eachfield (identified as fields l and II) are required to define a singlepicture element. As a consequence, the display comprises an array of 96pictureelements in the X direction (two lines per element) and 128elements in the Y direction along a line.

The radiation field scanned by the probe is likewise comprised of anarray of l 2,288 elemental areas arranged in an array 96b 128, with the96 elemental areas being arranged in the X direction. The size of the TVdisplay is fixed, but the actual size of the radiation field that can bescanned to provide this display will vary in size according to the linespacing of the probe and the speed at which scanning takes place.

The width of each elemental area (termed the preset distance) isestablished by the scan speed which is a function of the line spacing(which spacing depends on the collimator being used) and the maximumcount that the scan of any elemental area is to yield. In usual cases,the distance between the operator selected limits X1 and X2 will be lessthan 96 times the pre-set distance with the result that less than 96elemental areas will be scanned during the traverse of the probe from X1to X2 permitting the limits to be increased if necessary. The X addressof an elemental area is thus the number of preset distances of theelemental area from XI. The Y address of an elemental area is the numberof preset distances from Y1. Once the scan parameters are set, theoutput of encoder 182 can be processed by logic 40 as shown in FIG. 4 toproduce one pulse each time the probe traverses a distance equal to thepreset distance in the X direction; and the output of the encoder 19 canbe processed by logic 41 to produce one pulse each time the probetraverses a distance equal to the preset distance in the Y direction.

The X address of the probe is derived as shown in FIG. 4 in counter 42,and the Y address is derived in counter 43. To facilitate theexplanation, it will be assumed that counter 42 counts from 0-95 beforeoverflowing, that counter 43 counts from 0-127 before overflowing, andthat both counters are cleared when the limits X1 and Y1 are selected.In such caseythe contents of these counters, when a preset distancepulse occurs, will be the address of the elemental area whose scanninghas just been completed. Such a pulse enables gate 44 whereby thecontents of counter 42 is transferred to buffer register 45 and thecontents of counter 43 is transferred to the buffer register 46. Thus,these buffers will contain the address of the last elemental areascanned by the probe.

The count (i.e., the number of radiation stimuli detected by the probe)associated with an elemental area is accumulated in counter 50associated with the detector 9 of the probe. The occurrence of a presetdistant pulse enables gate 51 transferring the contents of counter 50into a buffer register 52 in preparation for transfer into memory 13.

sisssr b in det bel w. emqry comprises 12,288 shift registers, one foreach picture element of the display and elemental area of the scanfield.

Turning now to the details of memory 13, it is organized into 96syllables of l 2 8 wordseach. A memory word is constituted by thecontents of an 8-bit solidstate shift register permitting a count rateas high as 255 to be stored in any register. There are thus 12,288serially connected shift registers in the memory 13, each of whichtransfers its contents to an adjacent register upon receipt of a shiftpulse in shift line 100. After 12,288 shift pulses, the contents ofregister 55 at the input end of the memory will have circulated throughall of the registers of the memory and returned again via register 64 atthe output of the register.

The memory can be shifted whenever gate 62 is enabled to permit a 3,024MHz clock to be gated into the shift line 100. This gate is enabled byeither a G1 control pulse (see FIG. 7) that occurs during a G4 controlpulse (field shift mode of operation of the memory) or a G5 controlpulse (retrace shift mode of operation). In the field shift mode, atotal of 12,288 shift pulses are applied to shift line in 96 groups of128 pulses each. The first shift pulse occurs approximately 11 usfollowing the horizontal sync pulse associated with the 34th line of theraster on the TV tube; and the last pulse occurs about 10 ,us before thehorizontal sync pulse associated with the 227th line of the raster. Inthe retrace shift mode, which is used for synchronization of the memory,sufficient pulses are applied to cause the memory address register toreach the equivalent of 12,288 (i.e. counter 53 contains the number 95and counter 54 contains the number 127).

Synchronization of the memory with the initiation of the generation of araster on tube 14 is achieved by detecting the presence of a code wordin register 64 of memory 13. When this register contains the code word,it is sensed by decoder 101 enabling both of gates 102 and 103associated with the memory address register and depositing the contentsof shift counter 104 into counter 53 and the contents of shift counter105 into counter 54. Each of counters 104 and 105 will be reset when thelimits X1, X2 and the limits Y1, Y2 are established by the operator.Consequently, if no override of these limits has occurred, the presenceof the code word in register 64 will reset each of counters 53 and 54.

This approach achieves synchronization of the memory with the rastergeneration because each register of the memory, when the latter enters anew field shift mode, will have the same contents as when the memoryentered the previous field shift mode, unless of course data had beenadded by gate 56 during the previous field shift mode of the memory.Consider that the memory is out of synchronism with the rastergeneration, and that the code word is detected by decoder 101 betweenlines 34 and 267, for example, about line 40. In such case, the counter53 may contain the number 3 and counter 54 may be cleared. But theenabling of gates 102 and 103 by decoder 101 will change the contents ofcounter 53 to the number 95 and the contents of counter 54 to 127. Theremaining shift pulses applied to the memory address register during thegeneration of lines 41 through 227 will be counted so that when thememory completes its field shift mode, the counter 53 and 54 willcontain the complement of the numbers at which the code word wasdetected. Now, the memory enters its retrace mode. After 1 1,520 pulses,this mode will terminate because the contents of counters 53 and 54 willbe 95 and 127 respectively. When the memory again enters its field shiftmode, the code word will be contained in register 64, and the memorywill be in synchronism.

The code word is in reality a word forbidden for use as a data word. Forexample, it can be the number 255 if counter 50 is denied the ability tocount to this number. In such case, the highest count that can beaccumulated is 254 (corresponding to 255 stimuli in an elemental area).The code word is inserted into register 55 of the memory when gate 106is enabled by the operator as he prepares to start a scan by clearingthe memory. Once the code word is inserted, shifting of the memory willalways be halted, in the absence of a shift beyond the preset limits,with the code word contained in register 64 as the memory enters a fieldshift mode. Note that the detection of the code word when the memory isin its retrace shift mode occurs when gate 107 is disabled thus blockingthe transfer of the contents of registers 104 and 105 into counters 53and 54 respectively.

The picture elements on the TV tube are modulated in accordance with thecontents of the memory using th e line refresh register 67 whichcomprises 128 shift registers and accomodates one complete syllable ofthe memory. Shifting of the register 67 occurs when the 3,024 MHz clockis gated into the shift line 108 by enabling gate 68 with gate signalG2. As seen from FIG. 7, a G2 gate pulse occurs after each horizontalline sync signal. From a further inspection of FIG. 7, it can be seenthat during the first G1 gate pulse, during which the contents ofregister 70 are transferred into syllable register 71, etc. of memory13, the contents of syllable register 70 will also be transferred intoregister 67 through gate 65. During this first G1 gate pulse, gate 109is disabled by control signal G3, so that the previous contents ofregister 67 are lost. When the next G2 gate pulse appears, 128 shiftpulses are applied to register 67 circulating the contents through theregister exactly once because, in this interval of time, gate 109 isenabled by the G3 control signal. During this circulation, no shiftingof the registers of memory 13 occur. When the next G2 gate signalappears, the above described process is repeated.

The contents of output register 72 of the line refresh register 67 iscoupled to logic memory 73 through a gate 74 whenever the G2 pulse ispresent or whenever the G4 pulse is not present providing blanking ofthe electron gun means of the television tube except when data is to bedisplayed. In this manner, the output of logic means 73, when convertedto an analogue signal in digital-to-analogue converter 75, can be usedto modulate the picture elements on the TV screen. The contents ofregister 72 change every 328 during a G2 pulse as the 128 registers ofthe line refresh register 67 are circulated through one cycle inapproximately 42.4 u see. in synchronism with the generation of one lineof the raster. The data are displayed on each of two successive lines ofsuccessive fields of the raster as shown in FIG. 8.

The digital signal at the input to logic means 73 is representative ofthe raw data contained in the memory, i.e., the count at each elementalarea of the scanned radiation field. Such data can be processed by logicmeans 73 to subtract from the number at the input a constant quantityrepresentative of background noise, for example, so that the output oflogic means will be such as to enhance an understanding of the display.By providing manual adjustment for the logic means, the operator may trydifferent subtractions in an effort to optimize the display, all withoutdisturbing the original data. Alternatively, the logic means may provideother data processing operations such as selection of registers in thememory with counts within a predetermined range, and the display oftheir location. As a further alternative, logic means 73 and convertercan be arranged so that the output of the converter can drive a color TVtube in which the color of a picture element is a measure of the count.For example, high counts can be displayed in red and low counts incolors at the other end of the spectrum. In such case, suitablematrixing of the analogue signals is required.

As pointed out above, the time required to obtain the count of theradiation stimuli emanating from a given elemental area of the scannedradiation field is considerably longer than the time required to presentthe contents of the memory 13 to the TV tube 14 for display purposes. Infact, the contents of the memory is displayed on the tube 60 times persecond, while the scan of an elemental area is in the order of magnitudeof seconds. Furthermore, the buffer register 52 associated with theprobe counter 50 may have access to the memory at the current address ofthe probe 60 times per second with the result that the count associatedwith a given elemental area is inserted into the memory and displayed onthe TV tube substantially at the same time the data is acquired by theprobe.

By inspection of the TV tube, as shown in FIG. 1, the operator canascertain the current location of the probe relative to the organ beingmapped. As indicated in FIG. 1, where the phantom lines 80 represent theoutline of an organ being mapped, the operator can watch the map of theorgan being built up, picture element by picture element. By reason ofthe operation of the logic means 73, the display seen by the operatorwill be enhanced in the usual manner (e.g. background subtraction)permitting the operator to ascertain very early in the scanning of theradiation field whether the proper scanning parameters have beenselected. The adjustment to logic means 73 provides a convenient way inwhich the operator may try various types of processing while the scan isbeing carried out on the patient in order to quickly ascertain whetherthe scan should be continued or restarted with new scan parameters. Atall times, the data originally obtained by the detector and deposited inthe memory remains unchanged despite the different processing which isavailable by reason of logic means 73.

By inspection of the display on tube 14, the operator can also ascertainwhether the entire organ is being mapped, or whether a portion of theorgan, which possibly may contain medically interesting information,will be included in the map. In the event the limits of the probe mustbe changed, the procedure described in connection with FIG. 3 may befollowed. In such case, the probe will eventually travel beyond theoriginal limit and the preset distant pulses obtained from sealers 40and 41 will be accumulated in the registers 104 or 105. Each time thecode word is detected by decoder 101, the contents of register 104 willbe transferred into counter 53, and the contents of register 105 will betransferred into counter 54. Thus, at the end of a field shift mode ofthe memory, the code word will be contained in register 64 of memory 13,but the memory address register, composed of counters 53 and 54, will bedifferent from zero. When line 230 of a field is detected, the memorygoes into its retrace shift mode in which sufficient pulses are appliedto the memory address register to cause the counter 53 to stop when itcontains the number 95, and the counter 54 to stop when it contains thenumber 127. At this point in time, the code word will no longer be inregister 64 of the memory, but will in fact have been shifted to a newlocation in the memory determined by the contents of the shift counters104 and 105. When the memory again begins its field shift mode at line34 of the next field, the data contained within memory 13 will besynchronized with the initiation of the generation of the raster suchthat the data acquired by the probe beyond the original limits will bedisplayed at the proper spatial location with respect to the datapreviously acquired by the memory.

In order to illustrate the manner in which this type of synchronismoccurs, reference is made to FIG. 5, and in particular to portion (a) ofthe figure which shows a radiation field divided into elemental areas asdetermined by the scan parameters selected by the operator. Forsimplicity, it is assumed that the probe scans from the elemental areahaving address 0,0 (i.e., X=O, Y=O) toward the limit X2 acquiring thecount A" after completing the scan of the elemental area having theaddress 1,0, etc. Actually, the scan may start at any location in thefield. Portion (b) of FIG. 5 shows in schematic form the functionalrelationship of a group of registers of memory 13, the code word 255being inserted in the register at memory address 0.0 (i.e., row 0,column 0 of the picture elements). When count A has been acquired, it isimmediately inserted into address 1,0 of the memory which corresponds torow 1, column 0 of the picture elements. After count B has beenacquired, the limit X2 is reached and the probe is first driven in the Ydirection and then toward the limit X1 eventually completing the scan ofthe elemental area whose address is 2,1 and acquiring the count C whichis also inserted in the memory.

As shown in portion (c) of FIG. 5, the rastor begins at the lowerleft-hand corner of the TV tube and the lines are oriented vertically.As soon as count A is acquired by the memory, it is immediatelyprocessed and available for display as follows. In the next fieldfollowing acquisition of this count, no modulation will be applied tothe tube during the generation of the first 34 lines of the raster; andno modulation will be applied during generation of line 35, since atthis point in time there is no data contained at row 0 of the memoryregisters. When lines 36 and 37 of the field are generated, the picturetube will be modulated for 328 us with the contents of the memory atadress 1,0 producing a display of the count as processed by the logicmeans. The scan acquisition of data and display of the contents of thememory point-by-point as shown in portion (c) of FIG. 5.

Assuming now that the operator has decided that he would like to extendthe scan to covera region to the left of limit X1, and in particular theelemental area 99 whose adress is l ,0. Counter 42 considers thisaddress as 95,l and it is in this address that the count F is stored assoon as it is acquired. The shift of the probe beyond the limit X1 byone preset distance causes a l to be inserted in the counter 104 (inthis case the number 95). After the code word in register 64 isdetected,counter 53 is set at 95 and counter 54 is set at 0 since no shiftingbeyond the Y limit has occurred. The next retrace shift mode of thememory will cause the code word to be displaced to register 98 ofsyllable register 71 on the memory. Count F, however, will be containedin register 97 of syllable with the result that the display will havethe form shown in portion (d) of FIG. 5. Thus, the original display (c)has been shifted to the right (d) by the same number of preset distancesas the probe has progressed leftward beyond the original limit X1. Inthis manner, the video-displayprocessor of the present inventionautomatically accommodates itself to a change in the scan limitspermitting the scan to be enlarged beyond that originally set. Thisfeature eliminates the need to start a new scan in the event of apositional error in the original scan limits.

It will be apparent to those skilled in the art that the invention isapplicable to TV systems other than the 525 line system and which havedifferent frequencies for the horizontal and vertical sync pulses.Further more, more or less than 192 lines of the TV tube can be utilizedfor the display, which may start at some line other than line 34.

It should also be apparent to those skilled in the art that theparticular code word described above is not significant and that othercode words could be used. As

a matter of fact, several different code words could be utilized for thepurpose of shifting the mode of operation of the logic means if this isconsidered to be desirable.

As a further modification means may be provided for injecting into thememory 13, at the proper location, data which will permit a cross-hairvisual pattern to be displayed on the tube at a fixed or movablelocation. In such case, the logic means 73 may provide for obtaining theactual count of any picture element of the display utilizing thecross-hair pattern for identification purposes.

Another advantage of the present invention is the retention in thememory, subsequent to its acquisition, of all of the data acquiredduring scanning of the radiation field. This raw data, which can beprocessed as determined by the operator during scanning, then may betransferred and stored on a magnetic tape for later processing anddisplay. Having a processed display available in real time is medicallyadvantageous and is a primary advantage of the present invention.

As indicated previously, the memory 13 utilizes a plurality of solidstate shift registers. In the preferred form of the invention, the basiccomponent of the memory is a MOS-dynamic shift register of the typecurrently manufactured by Intel Corporation and designated l4Q4A,containing 24 bits per package. with an 8 bit word, one package defines128 words or one syllable. With this type of memory component, the straycapacitance associated with the gates of the MOS- transistors is used tostore information. Such memory components, however, require some minimumfrequency of shifting in order to prevent the loss of information. Inthe present invention, the approximately 4 ms between the end of onefield (line 226) and the beginning of the next field (line 34) might,under some conditions, result in the loss of information in the memorywere it not for the retrace shift mode of operation of the memory. Suchmode of operation thus achieves two results: it shifts the memory toprevent loss of stored information, and it provides synchronization asdescribed above. It is possible, of course, to utilize dynamic shiftregisters that will maintain their stored information without beingshifted during the 4 ms interval referred to above; and static shiftregisters can also be used. In either of these cases, synchronizationcan be achieved during the second field of every frame rather thanbetween fields as shown in the drawings.

What is claimed is:

1. A video-display-processor for producing an on-line display ofdistribution density of radiation stimuli emitted by a radiation field,comprising:

a. a probe for detecting the stimuli and a counter for accumulating thenumber of stimuli detected;

b. motorized means to cause the probe to traverse the field andsequentially scan a preselected number of elemental areas, each having apreselected size, for causing the probe counter to accumulate the numberof stimuli that occurred during the scan of each elemental area;

c. a memory;

d. means for transferring into the memory the number of stimuliaccumulated during the scan of each elemental area upon the completionof the scan thereof;

e. a TV display having a CRT with a viewing screen and means to.periodically generate a raster of modulatable picture elements on thescreen prior to completion of the scanning of all of the elemental areasof the field; and

f. means for modulating the picture elements in accordance with thecontents of the memory.

2. A video-display-processor according to claim 1 wherein the means forgenerating the raster generates interlaced fields of lines, each pictureelement comprising a portion of two sequential lines of the other field.

3. A video-display processor according to claim 1 wherein the memory isa solid state memory.

4. A video-display-processor according to claim 1 wherein the memorycomprises a plurality of shift registers, each of which is associatedwith respective elemental areas of the radiation field, and the contentsof the probe counter, upon completion of the scan of an elemental area,is transferred to the register associated with the last mentioned area.

5. A video-display-processor according to claim 4 including means tocirculate the memory through one complete cycle by shifting the contentsof the registers in synchronism with the generation of the raster.

6. A video-display-processor according to claim 5 including means tocirculate the memory through one complete cycle beginning apre-determined period of time subsequent to initiation of the generationof a raster and ending before the completion thereof, a memory addressregister incremented on each shift of the memory, means to shift thememory before the generation of the next raster is initiated and untilthe memory address register contains a number equal to the number ofshifts required to circulate the memory through one cycle, means toinsert a code word in one of the registers, and means responsive todetection of the code word during circulation of the memory forresetting the memory address register.

7. A video-display-processor according to claim 6 including limitselector means adjustable prior to the start of the scan of theradiation field to establish an initial limit of traverse of the probein a given direction, and adjustable subsequent to the start of the scanbut before the scan of all of the elemental areas is completed foroveriding the initial limit, a shift counter responsive to an overide ofthe initial limit for counting the number of elemental areas beyond theinitial limit scanned by the probes, and means for inserting thecontents of the shift counter into the memory adress register when thecode word is detected.

8. A video-display-processor according to claim 7 including a probeaddress register incremented by the traverse by the probe of radiationfield and whose contents at the completion of the scan of an elementalarea constitute the address of such area, comparator means for comparingthe contents of the probe address register at the end of the scan of anelemental area with the contents of the memory adress register andtransferring the contents of the probe counter into the memory when thecontents of the probe address register and the memory address registerare equal.

9. A video-display-processor for producing an on-line display of thedistribution density of radiation stimuli emitted by a radiation field,comprising:

a. a probe for detecting stimuli and a counter for accumulating thenumber of stimuli detected;

b. motorized means to cause the probe to traverse the field andsequentially scan a preselected number of elemental areas, each having apreselected size, for causing the probe counter to accumulate the numberof stimuli that occur during the scan of each elemental area;

c. a plurality of memory registers respectively associated with theelemental areas of the radiation field;

(1. means responsive to completion of the scan of an elemental area ofthe radiation field for transferring the contents of the probe counterinto the memory register associated with the scanned elemental area;

e. a TV display having a CRT with a viewing screen, electron gun meansfor generating at least one electron beam, and deflection means forcausing the beam to periodically generate a raster on the screen;

f. logic means to sequentially sample the contents of the memoryregisters in synchronism with the generation of the raster for producingprocessed data without changing the contents of the memory registers;and

g. a digital-to-analogue converter to convert the processed data into acontrol signal for modulating the beam while it generates the raster.

10. A video-display-processor according to claim 9 wherein the logicmeans subtracts a constant from the number sampled from each memoryregister to produce a processed number which is supplied to thedigital-to-analogue converter without changing the original number inthe memory register.

11. A video-display-processor according to claim 9 wherein the screenproduces colored light, the hue of the light produced by a pictureelement being determined by the amplitude of the output of the converterwhen the picture element is scanned by the beam.

12. A video-display-processor according to claim 9 wherein thesynchronization of the sampling of the contents of the memory registerby the logic means with the generation of the raster causes themodulation of the beam to produce a display area on the screen coveringless than the entire raster.

13. A video-display-processor according to claim 12 including means formanually selecting the memory register that is sampled when the beamreaches the display area of the screen.

14. A video-display-processor for producing an online display of thedistribution density of radiation stimuli emitted by a radiation field,comprising:

a. means to scan the radiation field for detecting and counting stimuliproduced by elemental areas of the field;

b. a plurality of memory registers respectively associated with theelemental areas of the field;

c. means responsive to the scan of an elemental area of the field forstoring a number representing the stimuli counted during the scan ofsuch elemental area in the register associated therewith;

d. a TV display having a CRT with a viewing screen, electron gun meansfor generating an electron beam means, and a deflection circuit forcausing the beam means to periodically scan the screen and generate aflicker-free raster;

e. logic means to sequentially read-out the memory registers,non-destructively, in synchronism with the scan of the screen forproducing digital data functionally related to the contents of theregisters; and

f. means responsive to the digital data for modulating the beam means inconformity therewith.

15. A video-display-processor according to claim 14 wherein the screenproduces colored light, the modulation of the beam means changing thecolor of the light produced by the screen.

16. A video-display-processor according to claim 14 including means forperiodically resynchronizing the reading-out of the memory registerswith the scan of the screen.

17. A video-display-processor according to claim 16 whereinre-synchronizing takes place at the end of the generation of eachraster.

=l i =l=

1. A video-display-processor for producing an on-line display ofdistribution density of radiation stimuli emitted by a radiation field,comprising: a. a probe for detecting the stimuli and a counter foraccumulating the number of stimuli detected; b. motorized means to causethe probe to traverse the field and sequentially scan a preselectednumber of elemental areas, each having a preselected size, for causingthe probe counter to accumulate the number of stimuli that occurredduring the scan of each elemental area; c. a memory; d. means fortransferring into the memory the number of stimuli accumulated duringthe scan of each elemental area upon the completion of the scan thereof;e. a TV display having a CRT with a viewing screen and means toperiodically generate a raster of modulatable picture elements on thescreen prior to completion of the scanning of all of the elemental areasof the field; and f. means for modulating the picture elements inaccordance with the contents of the memory.
 2. A video-display-processoraccording to claim 1 wherein the means for generating the rastergenerates interlaced fields of lines, each picture element comprising aportion of two sequential lines of the other field.
 3. A video-displayprocessor according to claim 1 wherein the memory is a solid statememory.
 4. A video-display-processor according to claim 1 wherein thememory comprises a plurality of shift registers, each of which isassociated with respective elemental areas of the radiation field, andthe contents of the probe counter, upon completion of the scan of anelemental area, is transferred to the register associated with the lastmentioned area.
 5. A video-display-processor according to claim 4including means to circulate the memory through one complete cycle byshifting the contents of the registers in synchronism with thegeneration of the raster.
 6. A video-display-processor according toclaim 5 including means to circulate the memory through one completecycle beginning a pre-determined period of time subsequent to initiationof the generation of a raster and ending before the completion thereof,a memory address register incremented on each shift of the memory, meansto shift the memory before the generation of the next raster isinitiated and until the memory address register contains a number equalto the number of shifts required to circulate the memory through onecycle, means to insert a code word in one of the registers, and meansresponsive to detection of the code word during circulation of thememory for resetting the memory address register.
 7. Avideo-display-processor according to claim 6 including limit selectormeans adjustable prior to the start of the scan of the radiation fieldto establish an initial limit of traverse of the probe in a givendirection, and adjustable subsequent to the start of the scan but beforethe scan of all of the elemental areas is completed for overiding theinitial limit, a shift counter responsive to an overide of the initiallimit for counting the number of elemental areas beyond the initiallimit scanned by the probes, and means for inserting the contents of theshift counter into the memory adress register when the code word isdetected.
 8. A video-display-processor according to claim 7 including aprobe address register incremented by the traverse by the probe ofradiation field and whose contents at the completion of the scan of anelemental area constitute the address of such area, comparator means forcomparing the contents of the probe address register at the end of thescan of an elemental area with the contents of the memory adressregister and transferring the contents of the probe counter into thememory when the contents of the probe address register and the memoryaddress register are equal.
 9. A video-display-processor for producingan on-line display of the distribution density of radiation stimuliemitted by a radiation field, comprising: a. a probe for detectingstimuli and a counter for accumulating the number of stimuli detected;b. motorized means to cause the probe to traverse the field andsequentially scan a preselected number of elemental areas, each having apreselected size, for causing the probe counter to accumulate the numberof stimuli that occur during the scan of each elemental area; c. aplurality of memory registers respectively associated with the elementalareas of the radiation field; d. means responsive to completion of thescan of an elemental area of the radiation field for transferring thecontents of the probe counter into the memory register associated withthe scanned elemental area; e. a TV display having a CRT with a viewingscreen, electron gun means for generating at least one electron beam,and deflection means for causing the beam to periodically generate araster on the screen; f. logic means to sequentially sample the contentsof the memory registers in synchronism with the generation of the rasterfor producing processed data without changing the contents of the memoryregisters; and g. a digital-to-analogue converter to convert theprocessed data into a control signal for modulating the beam while itgenerates the raster.
 10. A video-display-processor according to claim 9wherein the logic means subtracts a constant from the number sampledfrom each memory register to produce a processed number which issupplied to the digital-to-analogue converter without changing theoriginal number in the memory register.
 11. A video-display-processoraccording to claim 9 wherein the screen produces colored light, the hueof the light produced by a picture element being determined by theamplitude of the output of the converter when the picture element isscanned by the beam.
 12. A video-display-processor according to claim 9wherein the synchronization of the sampling of the contents of thememory register by the logic means with the generation of the rastercauses the modulation of the beam to produce a display area on thescreen covering less than the entire raster.
 13. Avideo-display-processor according to claim 12 including means formanually selecting the memory register that is sampled when the beamreaches the display area of the screen.
 14. A video-display-processorfor producing an on-line display of the distribution density ofradiation stimuli emitted by a radiation field, comprising: a. means toscan the radiation field for detecting and counting stimuli produced byelemental areas of the field; b. a plurality of memory registersrespectively associated with the elemental areas of the field; c. meansresponsive to the scan of an elemental area of the field for storing anumber representing the stimuli counted during the scan of suchelemental area in the register associated therewith; d. a TV displayhaving a CRT with a viewing screen, electron gun means for generating anelectron beam means, and a deflection circuit for causing the beam meansto periodically scan the screen and generate a flicker-free raster; e.logic means to sequentially read-out the memory registers,non-destructively, in synchronism with the scan of the screen forproducing digital data functionally related to the contents of theregisters; and f. means responsive to the digital data for modulatingthe beam means in conformity therewith.
 15. A video-display-processoraccording to claim 14 wherein the screen produces colored light, themodulation of the beam means changing the color of the light produced bythe screen.
 16. A video-display-processor according to claim 14including means for periodically resynchronizing the reading-out of thememory registers with the scan of the screen.
 17. Avideo-display-processor according to claim 16 wherein re-synchronizingtakes place at the end of the generation of each raster.